With the development of human-computer interaction technology, touch technology is increasingly used in a variety of displays. Capacitive touch technology is widely used due to its advantages of wear resistance, long service life, low maintenance cost for user, and capability of supporting gesture recognition and multi-touch.
Capacitive touch technology can be classified into self-capacitance touch technology and mutual capacitance touch technology depending on the detection method of capacitance between objects. Through the self-capacitance touch technology, presence, location and movement of an input object on a touch screen is detected according to change in capacitance between the input object and an electrode. Through the mutual capacitance touch technology, presence, location and movement of an input object on a touch screen is detected according to change in capacitance between electrodes caused by the input object.
In the prior art, no matter it is the self-capacitance touch technology or the mutual capacitance touch technology, a common electrode in an array substrate can be reused as a touch electrode. In a display stage, a common electrode signal is input to the common electrode; and in a touch stage, a touch signal is input to the common electrode. Both of the signal transmission and polarity detection of the common electrode are realized through touch lines.
Specifically, referring to an array substrate 100 in the prior art as shown in FIG. 1, the array substrate 100 has a side length along a direction Y larger than a side length along a direction X. The array substrate 100 includes a plurality of common electrodes 110, which are reused as touch electrodes. Each of the common electrodes 110 is electrically connected through a via hole 130 to a touch line 120 extending along the direction Y, and is electrically connected to a touch control IC140 through the touch line 120. The touch control IC140 transmits common electrode signals or touch signals to the common electrodes 110 through the touch lines 120 for display or touch detection.
In order to improve the display and touch yield of the array substrate 100, the touch performance and display performance of the common electrodes 110 are detected. As shown in FIG. 2, in order to perform the detection of the touch performance and display performance of the common electrodes 110, test lines and switch elements 150 are further provided. Each touch line 120 is electrically connected to a first electrode of one switch element 150. Control terminals of the switch elements 150 are electrically connected to a test line 160C. Second electrodes of the switch elements 150 are electrically connected to a test line 160A or a test line 160B. During test, the test line 160C inputs a control signal to the switch elements 150 to turn on the switch elements 150, and the test line 160A or the test line 160B inputs a different voltage. During display and touch, the switch elements 150 are turned off, and the common electrodes 110 are electrically connected to the touch control IC140 through the touch lines 120 as shown in FIG. 1.
However, in the prior art, such configuration of the array substrate 100 can cause the following problems:
1) A touch line electrically connected to a top common electrode has a resistance much larger than that of a touch line electrically connected to a bottom common electrode, resulting in poor visibility at the top end when displaying a harsh image (e.g., performing dot check/pixel check).
2) The above difference in resistance cannot be eliminated by shorting the common electrodes through the switch elements and the test lines.
3) For a display panel of a large size (8 inches and above), the larger the difference in resistance, the more significantly the display effect will be negatively affected.